Some products are delivered and sold in containers for use by customers. For example propane is often sold in containers that are valved cylinders such as the type typically used for outdoor grills. These valved cylinders have a cylindrically shaped tank, a base-mounted to the bottom of the tank, a valve at the top of the tank, and a guard substantially encircling the valve and providing a pair of lifting handles. The base and the guard have diameters smaller than the diameter of the outer surface of the tank. Because of the specific nature in which such canisters must be filled, the equipment needed to fill the tanks and the highly combustible nature of propane, it is generally required that a professional fill a user's propane tank.
Accordingly, for propane and similar products, empty canisters are exchanged for full ones. Generally, when a propane canister is empty (i.e. substantially out of propane or another product), a user brings their canister to a particular store and exchanges their empty canister for a full canister (i.e. full or substantially full of propane or another product). A cashier generally assists the user in ensuring that the user exchanges their empty canister for a different full canister. The full and empty propane canisters may be kept in various secure locations (e.g. locked cage, etc.). Additionally, the propane canisters are generally also stored outside the store for various safety reasons.
Exchanging the propane canisters can be a hassle for the businesses that handle the canisters in that the cashier may have to leave their register to go and exchange the canisters. This can also result in customers waiting at the register unassisted or the businesses needing to constantly ensure that an employee is available to exchange propane tanks. For these as well as other reasons, various attempts have been made to automate the process of obtaining or exchanging canisters such as propane canisters. Unfortunately, these automated canister distribution system have generally been insufficient to meet the needs of the market. Often they require the participation of a cashier or other store personnel and, thus, represent no advantage over traditional manual canister cages. Also, some systems have failed to effectively address the issues related to preventing a purchaser from removing more than one full canister or an empty canister from the automated system or from preventing a purchaser from returning false or fake empty canisters. For these and other reasons, there is a demand for a more practical and efficient system for obtaining a full propane canister or exchanging an empty canister for a full canister.